ITO is widely utilized as a conductive material for electrodes that are used in display devices such as liquid crystal displays, organic EL's and touch panels, and in integrated type solar cells and the like. However, there are problems such as the small reserves of indium metal, the color tinge caused by low transmittance in the long-wavelength region, the need for a high temperature heat treatment for reduction of resistance, and the lack of flexibility.
Under such circumstances, an investigation of a conductive member using a metal nanowire has been reported (U.S. Patent Publication No. 2007/0074316), and from the viewpoint of excellent transparency, excellent low resistance and excellent reduction of the amount of metal used, there is an increasing expectation of using metal nanowire in place of ITO. However, problems have been found regarding metal nanowire such as the haze value being high due to its wire structure; heat resistance being insufficient due to the specific surface area of the metal being high; and, even though practical durability cannot be obtained unless coating of a photocurable resin or the like is applied to the outermost layer that contacts air, the occurrence of an increase in resistance and a decrease in uniformity in the in-plane resistance as a result of the coating.
Among these, an improvement in haze characteristics is one important problem, and attempts have been made to provide a solution by sufficiently eliminating impurities by, for example, an ultrafiltration method or the like (U.S. Patent Publication No. 2009/0321634 and Japanese Patent Application Laid-Open (JP-A) No. 2009-129732); however, it cannot be said that the effects thereof are sufficient, and a further improvement is desired.